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Biomedical subjects

I Imamura

Publications and source records attributed to I Imamura.

At least 55 records · Page 3Linked to original sources
PubMed1990

Immuno-cross-reactivity of histidine and dopa decarboxylases.

Immuno-cross-reactivity between histidine decarboxylase (HDC) and dopa decarboxylase (DDC) was investigated. By comparing the cDNA sequences of rat HDC with rat and guinea-pig DDCs, we found a region that may possibly be related to the cross-reactivity of anti-rat HDC antibody with guinea-pig DDC. The peptide encoded by this region was synthesized and anti-peptide antibody was prepared. We also purified HDC and DDC homogeniously from fetal rat liver and guinea-pig liver, respectively. On immunoblotting, anti-peptide antibody recognized both rat HDC and guinea-pig DDC. Anti-HDC polyclonal antibody which also recognizes both enzymes detected only rat HDC when it was absorbed by the peptide. This result indicates that this region is responsible for the immuno-cross-reactivity of anti-rat HDC antibody with guinea-pig DDC.

Amino Acid Sequence↗
PubMed1990

Molecular cloning of guinea-pig aromatic-L-amino acid decarboxylase cDNA.

Guinea-pig aromatic-L-amino acid decarboxylase (DOPA decarboxylase, DDC), but not rat DDC, reacts with the antibody against rat histidine decarboxylase (HDC). For determination of the molecular reaction for this cross-reactivity, a cDNA clone of guinea-pig DDC was isolated. Guinea-pig DDC consists of 480 amino acids and its molecular weight is 54,148. The sequence identify of guinea-pig DDC with rat DDC is 86%. Guinea-pig DDC has a region showing 100% sequence identity with rat HDC, but only 67% sequence identity with rat DDC, suggesting that this region is related with the cross-reactivity of guinea-pig DDC and anti-rat HDC antibody.

Amino Acid Sequence↗
PubMed1989

Molecular cloning and sequencing of a cDNA of rat dopa decarboxylase: partial amino acid homologies with other enzymes synthesizing catecholamines.

Dopa decarboxylase (DDC; aromatic-L-amino-acid decarboxylase; aromatic-L-amino-acid carboxylase, EC 4.1.1.28) was purified from rat liver and its partial sequence was determined. Synthetic oligonucleotides were used to construct and screen rat liver cDNA libraries, and three clones were isolated and sequenced. The 2 kilobases of DDC cDNA cloned consisted of a 5'-noncoding segment of 78 nucleotides, a coding region of 1440 nucleotides, and a 3'-noncoding region of 438 nucleotides. The encoded protein of 480 amino acid residues had a molecular weight of 54,000. A special feature of the primary structure of rat DDC was a repeating structure consisting of 29 amino acid residues. A sequence of 58 amino acid residues, including this repeating structure of rat DDC, was found to show homologies with those of rat tyrosine hydroxylase, human dopamine beta-hydroxylase, and bovine phenylethanolamine N-methyltransferase, other mammalian enzymes that synthesize catecholamines. These results indicate that catecholamine biosynthetic enzymes are structurally related and suggest that their homologous domains are important for catechol-protein interactions.

Amino Acid Sequence↗
PubMed1986

Chemical modification of tryptophanase from E. coli with polyethylene glycol to reduce its immunoreactivity towards anti-tryptophanase antibodies.

Escherichia coli tryptophanase was modified with 2,4-bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine (activated PEG2, MW 5,000 x 2). The modified tryptophanase, in which approximately 43% of the total 120 amino groups and 38% of the total 16 sulfhydryl groups in the molecule were coupled, completely lost the immunoreactivity towards anti-tryptophanase serum from rabbit. Approximately 10% of the enzymic activity was retained. The modified enzyme showed the same physicochemical properties as the native enzyme: Km value for L-tryptophan (0.3 mmol/l), optimum pH (8.0) and optimum temperature (50 degrees C). The modified enzyme was more resistant than the native counterpart against proteolytic digestion with trypsin.

Animals↗
PubMed1985

N tau-Ribosylhistidine, a novel histidine derivative in urine of histidinemic patients. Isolation, structure, and tissue level.

On amino acid analysis of urine of histidinemic patients, an unidentified compound was eluted in a position between beta-aminoisobutyric acid and gamma-aminobutyric acid. This compound was purified to homogeneity from the urine by a combination of extraction with 80% ethanol, repeated column chromatography on Bio-Rad AG-50, and high performance liquid chromatography on a strongly cationic ion exchanger. The compound yielded free histidine on hydrolysis in an evacuated sealed tube with 0.1-6.0 M HCl at 145 degrees C for 5 h, but not at 100 degrees C for 24 h. This compound was determined to be N tau-ribosylhistidine by 1H and 13C NMR spectroscopies. The urinary content of this material in normal and histidinemic children was 17.8 +/- 13.4 (n = 10) and 126 +/- 51 (n = 14) mumol/g creatinine (mean +/- S.D.), respectively, and were closely correlated with those of urinary histidine. The renal clearance value of N tau-ribosylhistidine in humans was 96% of that of creatinine. When rats were fed on diets rich in histidine, the urinary excretion of N tau-ribosylhistidine increased greatly and was well correlated with the intake of histidine.

Amino Acid Metabolism, Inborn Errors↗
PubMed1985

Formation of N tau-ribosylhistidine, a novel histidine derivative found in the urine in histidinemia, from histidine and NAD(P)+ catalyzed by an NAD(P)+ glycohydrolase system.

The formation of N tau-ribosylhistidine (His-R), a novel histidine derivative found in the urine of histidinemic patients, was studied. A most possible synthetic pathway catalyzed by imidazole acetic acid (ImAA) phosphoribosyltransferase was not substantiated, because p.o. administration to humans and rats of aspirin, an inhibitor of the enzyme, did not change the urinary excretion of His-R, whereas aspirin decreased the excretion of ImAA-R with concomitant increase in that of ImAA. His-R was produced on incubation of a rat liver homogenate or its membrane fraction with histidine, NAD(P)+ and MgCl2, but not with only histidine or NAD(P)+. Nicotinamide inhibited the formation of His-R. Thus the enzymes responsible for the formation of His-R were suggested to be NAD(P)+ nucleosidase, nucleotide pyrophosphatase and 5'-nucleotidase.

5'-Nucleotidase↗
PubMed1984

The differential reaction of histamine and N tau-methylhistamine with Pauly's diazo reagent: application to assay of histamine N-methyltransferase activity.

A simple nonradioisotopic fluorescent method for assay of histamine N-methyltransferase (HMT) activity was developed. After termination of the HMT reaction, the remaining excess substrate, histamine, was degraded by Pauly 's diazo reagent, whereas the product, N tau-methylhistamine (N- MeHA ), was not degraded by the reagent. Then the mixture was applied to high-performance liquid chromatography under conditions in which N- MeHA was not separated from histamine, and N- MeHA was measured fluorometrically by condensation with o-phthalaldehyde. The method would be convenient for measurement of HMT activity during enzyme purification.

Animals↗
PubMed1984

Histamine metabolism in patients with histidinemia: determination of urinary levels of histamine, N tau-methylhistamine, imidazole acetic acid, and its conjugate(s).

Histamine metabolism in histidinemic patients was studied by measuring the urinary levels of histamine and its metabolites. The urinary excretions of histamine, N tau-methylhistamine, imidazole acetic acid, and its conjugate(s) were higher in patients with histidinemia than in controls, and these levels of excretion were correlated with the plasma histidine level. The urinary histamine levels of patients with eczema-like dermatitis were twice that of those without dermatitis. The urinary excretion of 3-methylhistidine showed a close correlation with the urinary histidine excretion. Thus, it was concluded that histamine metabolism is higher in histidinemic patients than in normal controls.

Amino Acid Metabolism, Inborn Errors↗
PubMed1984

Effect of food intake on urinary excretions of histamine, N tau-methylhistamine, imidazole acetic acid and its conjugate(s) in humans and mice.

The urinary excretions by young healthy men of histamine and its metabolites, N tau-methylhistamine, imidazole acetic acid, and imidazole acetic acid conjugate(s), increased 1-3 h after food intake. The increase was seen even after the intake of konnyaku (mannan) as a protein-deficient food, suggesting that physical stimulation of the gastric mucosa by food is the main cause of histamine release. This suggestion was confirmed by the following findings in patients and mice. In patients with stomach diseases, gastrectomy resulted in decreases in the excretion of histamine and its metabolites in the urine, and patients subjected to intravenous hyperalimentation excreted less histamine and its metabolites in the urine than normal subjects. In mice, a correlation of histamine excretion with food intake was demonstrated experimentally. Namely, mice fed only during the night (21:00-0:00) showed increased excretions of histamine and its metabolites at 23:00-3:00, whereas those fed in the morning (9:00-12:00) showed increased excretions of those compounds at 11:00-15:00. All these results are consistent with the idea that urinary histamine and its metabolites mainly originate from the stomach.

Adult↗
PubMed1984

Determination of imidazole acetic acid and its conjugate(s) levels in urine, serum and tissues of rats: studies on changes in their levels under various conditions.

A convenient and reproducible method for assay of imidazole acetic acid (ImAA) was developed as a modification of that described previously (Watanabe et al., 1983). ImAA conjugate(s) (ImAA-C), mainly consisting of imidazole acetic acid riboside, could be measured by this method after its hydrolysis to ImAA. The ImAA and ImAA-C levels in various tissues of rats were measured and the effects of various agents on these levels were studied. The renal clearance values of ImAA-C in rats and man were similar to the creatinine clearance values, but those of ImAA were 1/40 of those of ImAA-C, suggesting that the latter is readily excreted in the urine. Consistent with this idea, the urinary excretion of ImAA-C was found to increase much more than that of other histamine metabolites during late pregnancy, when the foetus produces much histamine.

Animals↗
PubMed1983

Method for enzymatic determination of imidazole acetic acid.

A method for enzymatic assay of imidazole acetic acid (ImAA) was developed, based on the strict substrate specificity of imidazole acetate monooxygenase from Pseudomonas sp. [Maki et al. (1969) J. Biol. Chem., 244., 2942-2950], which catalyzes concomitant conversion of NADH to NAD+. Thus, ImAA was determined by measuring decrease in absorbancy at 340 nm. Tissue extracts were partially purified and/or concentrated by column chromatography on Bio-Rad AG-1 before enzymatic assay. The lowest measurable level of ImAA by this method was 2 nmol.

Animals↗
PubMed1976

A simple hemostatic method in suprapubic prostatectomy: extracapsular pulling sutures.

To block the vessels of the prostate, extracapsular pulling sutures were placed from the 4 and 8 o'clock positions on the bladder neck to the perineum prior to enucleation in 25 cases of prostatectomy. The removable pulling sutures successfully reduced blood loss during and after prostatectomy. Besides, the average operating time was markedly shortened. Postoperative courses of the patients were uneventful on the whole and there was no remarkable complication.

Hemostasis, Surgical↗